Perhaps you should try some spelling variations:
tinh dung » trinh dung, tinh quang, tinh huong
hieu soat » hieu suat, hieu hoat, hieu luat
dung quan » dung quang, dung luan, luong quan
tuan soat » quan sat, toan hoat, tuan hoan
van hieu » cao hieu
quan van » luan van, quan va, quan luan
van tuan » van quan, van ban, anh tuan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tinh dung (luan OR lan) van hieu soat ) or ( tin dung quan van tuan soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tinh dung (luan OR lan) van hieu soat ) OR ( tin dung quan van tuan soat )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tinh dung (luan OR lan) van hieu soat ) or ( tin dung quan van tuan soat ))".
• Adding a wildcard symbol may retrieve word variants: (( tinh dung (luan OR lan) van hieu soat ) or ( tin dung quan van tuan soat ))*.